As a former Phoenix resident, I completely understand the resistance to speed cameras. They are always touted as a public safety measure, but widely regarded as little more than a revenue machine. In my experience, the trigger speed was always perilously close to the natural flow of traffic which (at least in the places where I have lived) is consistently the speed limit + some amount. The net effect was always a sudden, dramatic slowing of traffic in the camera zone followed by a return to business-as-usual.

Edit: I should clarify that these were freeway speed cameras. Maybe they are more effective as a safety device in pedestrian-heavy areas, but I have no experience with the cameras is that context.